Pneumatic-dbs



J. G. MACLAREN.

PNEUMAHC DESPATCH TUBE APPARATUS. APPLICATION man SEPT 28,1914. RENEWED NOV. 21, I916.

1,366,013. Patented Jan. 18, 1921.

3 SHEElS-SHLET I.

V I I A f --x. I :i p Y/ 1 I77 j v/ v l1 WITNESSES: I w NVENTOR.

' BY F J. G MACLAREN.

PNEUMATiC DESPATCH TUBE APPARATUS.

APPLICATION FILED SEPT 28, 1914. RENEWED NOV. 21, 1916.

1,366,013. Patented Jan. 18, 1921.

V 3 SHEETS-SHEET 2. Z

IIIIIIIIIIIIIIIIIIIII).

IN VEN TOR. WTNESSE W m W By WW V ATTORNEY 1 1. e. MACL'AREN.

PNEUMATIC DESPATCH TUBE APPARATUS.

APPLICATION man SEYPT 28,1914. RENEWED NOV. 21, ms.

1,366,013.. Patented Jan. 18,1921.

3 SHEETSS HEET 3.

fiya F79 57/0 6 I ,INVE'NTOR.

WITNESSES: 7 M W ATTORNEY 7 JAMES e. Marinas-Err, on rrnnnrson, new onx.

TbIaZZ w'ltm'n it mag monomer:

e it known that 1, JAMES G- NIAOLAREN, of Harrison, in the 1 county of 'Westchester andState of NewYork, have invented certain new and useful Improvements in Pneuinat'ic-Despatch l ube Apparatus, of which the following is a specification,

invention is more especially concerned with; a pneumatic despatch system which is aluways opento the transmission of carriers regardlessof whether other carrier's'are in transit, and in which system the air current", creating means for the propulsion of the invention relates to carrier systems of the pneumat c type for the transmission r of carriers 'betwe'ena central station, and

one or jinore outlying or sub-stations. My

carriersis required to operate no longer than is reqniredto deliver a carrier orcarriers throughthe portion of theftransitv tubes actually in use, H

My Invention, will best understood by reference'to the following description when tub . the apps takenin connection with certain specific illustrative embodiments thereof shown in 1 the arconipanyinfgdrawings, While its scope willbe more particularly pointed out the uppendedclaims.v V i In thefdrawings:

Figure. l is an elevation of One form of carrier transmiss on apparatus embodying 1 [detail riew partly in section of u, a transittube and one ji'orrn of electric 'circnitcontroller for causing the mainte- Jf 'ance ota 1 the preyiously' initiated air current vrates, said controller being will as. i Need;

Sis an enlarged detail view, in sectioin ofthe'circuit. controller as 'it appears .when tllQCll'Cl'llt is open;

isranlelevation of the form which -atus takes when thereis'a plural- "of transit tubes for despatching carriers ptrcn 'the central station to the sub-station, and another transit tube for despatchlng -.rs from. the sub-stations to the central nyinvention, illustrating a single transit" 1 meeting a central station with a subon of the apparatus," including a car-I t appears when {the circuit is ENEUMATIC-DESPATCH-TUBE AIEPARA'IUS.

Specification of Letters Patent: Patented Ja 18 1921 p licati filed'september as, 1914, Serial rib. 863.793. RenewedNovember 21, 1916. Serial No. 132,714.

* ne -rarest,forrice;

- Fig. 5 is a diagrammatic View of the electrical system of the apparatus; I

- Fig. '6 is an enlarged detail sectional view of the preferred electric circuit controller I employed in connection with the form of apparatus shown in Fig. 4;

F g. fr 199,11 enlarged detail sectional View of a check-valve formingla part of the apps;

ratus shown in Fig. 4; and

of electric circuit controllers in the form of manon eters connected to the transit tubes employing pressure below that of the atmosphere for thetransmission of carriers; and

Fig; 12 is anenlarged detail view in section of a portion of the transit tube and the trip which. momentarily closes the motor circuit.

Referring to the drawings, and to the specific embodiment of my invention which is illustrated in Figs. 1, 2, 3 and 12,1 have there shown a carrier apparatus of the pneumatic type having atransit tube B provided with a despatching inlet A open'to'tlieat. inosphere at 'one' station and leading therefrom to a discharge station where it isprovided Witha normally closed valve 'An' air current maybe created in this transit tube by suitable air current creating means,

1+ igs. Sand 9 are detailsectional views 0t" electric circuit controllers in the form of herein a. blower or punip B suitably connected to the transittube as by a pipe B. This blower or pump may be driven by suitable means, herc nhan electric motor- B rentte maintain theoperation of the motor so long as a carr errer'na ns in the system,

is unobstructed." In I the present instance.

these motor controlling devices include a" starting switch 13, an appropriatecontact maker C suitable magnetically operated to complete a circuit, to said switch, and a circuit controller E, the latter being shown in etail in Figs. 2 and 3. v V H The circuit controller-E, as herein shown,

95 and to stop the motor when the transit tube comprises a switch D, whose purpose is to cause the maintenance of the motor circuit previously established by the contact maker C. This circuit controller may be of any suitable consruction, and controlled by the differential pressure created by a carrier or carriers in transit. In other words, it may be operated by the changes of pressure in the sys em due to the presence and absence of carriers. As herein shown, the controller E is provided with a diaphragm chamber E* communicating through a pipe E with the transit tube B. In this form of my invention, this chamber 13* is provided with a flexible diaphragm E attached to a spindle E the latter being suitably connected to op- .erate the switch D.

In the present instance, when there is no carrier in the line and the air pressure on opposite sides of the. diaphragm E is balanced, the switch D is open as shown in Fig. 3. Vhen, however, owing to the presence or a carrier m in the line, the pressure within the transit tube B and the diaphragm chamber E becomes reduced to a point below that of the atmosphere, the latter, acting against the diaphragm E will cause the latter to operate the switch D to close the circuit and maintain the motor B in operation as long as a carrier remains in the line.' The diaphragm may be provided with suitable means herein a weight E to restore the diaphragm and switch to their normal position as soon as the pressure on opposite sides of the diaphragm again becomes balanced.

\Vhen the apparatus is in normal condition, the pump is at rest and hence atmospheric pressure exists throughout the transit tube, the pipe E and the chamber E. In other words, the'transit tube is normally dead. If now a carrier a: be inserted at the despatching inlet A, at the top of the vertical portion of the transit B, the carrier will descend by gravity until it strikes the trip C of the contact maker C, whereupon the latter will complete a circuit to the magnetically operated switch B thus causing the latter to complete a circuit to the motor B. The motor, thus started into operation, drives the pump B and the latter now commences to exhaust air from the pipe B, the pipe E, the chamber E, and that por tion of the transit tube B which is intermediate the carrier as and the outlet valve B.

This exhausting of air will reduce the internal pressure to a point below that of the atmosphere, and since the carrier is exposed on one end to atmospheric pressure, and on the other end to a pressure below that of the atmosphere, the carrier naturally will be propelled toward the discharge stat-ion B. This reduction of pressure Within the chamber E unbalances the equal pressures theretofore existing on opposite sides of the diaphragm E and since the atmospheric pressure on the outer face of the diaphragm now predominates over that .on its inner face, the diaphragm will at once move inward, thus closing the switch D. This closing of the switch D, following the completion of the motor circuit by the magnetically operated switch B will keep the motor in operation and thus maintain the previously initialed air current.

The motor will be kept in operation as long as the line remains obstructed by a carrier, and when the latter is delivered through the valve B", since atmospheric pressure can now have free access to the transit tube, the pipe E and the chamber E, the diaphragm E will resume its initial or normal position, thus opening the switch D, and causing the magnet switch B to become denergized and to break the motor circuit, thereby stopping the motor and the pump. The transit tube is new again in its normal condition, or dead. It should be understood, however, that the introduction of the first carrier at the inlet A can be followed by the introduction of successive carriers even though another or other carriers are en route, and that the operation of the pump will continue as longas a carrier remains in the transit tube.

It the transit tube B were extended, as shown by the dotted lines in Fig. 1, past the inlet A to the inlet A, it would be necessary to equip the latter witha contact maker C similar to the contact maker C, so that the dispatching of a carrier at the inlet A. will energize the magnetically o1 erated starting switch B The completion of the motor circuit will now start the motor in operation, and its operation will continue until the carrier reaches the vertical riser, whereupon, owing to the action of gravity upon the carrier, the latter in dropping will. acquire a velocity greater than that of the air current. This will be followed by a reduction of pressure at the point B, resulting in the stopping of the motor in the manner hereinbefore explained, and the motor will remain at rest until the carrier engages the trip C of the contact maker C, thus again completing the circuit in the manner already explained.

Referring now to Fig. 4, I have there shown another embodiment of my invention comprising a system of pneumatic dispatch tubes for the dispatch ofcarriers from substations P, P and P to a central station B. In this form, a transit tube B is provided, at the substations, with inlets G, G G and G for the introduction of carriers, and a discharge terminal B, the latter being provided with a valve B, through which the carriers will be delivered at the central station.

As a means for dispatching carriers from the central station to the various substations, I have herein provided a series of flaw transit tubes N. It will be understood that one blower might operate more than one set of transit tubes. The transit tubes N are herein connected by suitable check valves N,having flaps N and a pipe E to a cham ber E hereinafter described.

As a means for supplying air under pressure to any one of the transit tubes N at will, I have'herein provided a suitable swivel dispatching inlet 0, which permits the connection of any one of said tubes to the pressure side or outlet of a blower B, as in U: S. Letters Patent to Campbell No. 454,992, issued June 20, 1891. The check valves N will permit the admission of air under pressure from the particular transit tube N, which is connected with the blower, to the chamber ll of an electric circuit controller (Figs. 4; and 6), but will not permit this air to escape into the two remaining transit tubesN, whichare disconnected and open to the atmosphere, as illustrated for example in Fig. 4. Each of the check valves N is herein provided with a nozzle N connected by a suitable'pipe or rubber tube N with one of the transit tubes N.

Turning now-to the electric system which is the preferred means for the control of the pneumatic system, the pump or blower 1 2 is herein driven by a suitable electric motor B shown in Fig. 4:, and represented diagrammatically in Fig. 5, which is a diagram of the electric system. Referring to Fig. 5, power feeders and 14, indicated as positive and negative, lead from a suitable source of current, not shown. The positive wire 10 has a branch ll provided with taps 2 lead ing to terminals at one side of contact makers 1, 2, 3 and 4, located at the terminals G, G G and G respectively. The branch 11 continues past these contact makers, and is connected to one terminal of a switch D of a suitable circuit controller E. The other terminal of this controller is connected by a wire 12 and taps with the other terminals of the contact makers 1, 2, 3 and 4, respectively.

' T he wire 12 is continued past the contact makers, and is connected to one terminal of a coil K of an electro-magnet herein of the solenoid type, the other terminal oi which is connectedby a wire 13 with the negative wire 14:. If, now, the circuit be completed I by the closing of any one of the contact 55 makers 1, 2, 3 and 4, or by the switch D, the coil K will be energized, and when the circuit is broken, said coil will be deenergized.

is energized and the core is lifted, makes contact across a pair of jacks L, and when the coil is deenergized and the core drops, breaks said contact and then makes contactacross a pair of jacks K".

The primary switch is connected in turn to operate a suitable secondary switch as follows: he jacks K and L on one side are connected by branch wires 15 and 16 to the positive line 10. The jack L on the other side is connected by a wire 17 to one ter minal of coil 1, the other terminal of which is connected by a wire 18 to the negative line 14. Th remaining jack K is connected by a wire 19 to a spring yielding jack 9. The latter is a companion to a spring yielding jack 8, which is connected by wire 20 to one terminal of a coil M, which is a companion to the coil 1. The other terminal of the coil M is connected by a wire 21 to the negative line 14. V

The companion coils I and M have cores J pivotally connected to a lever K. carrying contact making pieces K. and K The contact making piece K cooperates with and closes the motor circuit across acks 6 and 7, one of which is connected to the negative line 1 while the other is connected by a wire 22 to one terminal of the motor 13*, the other terminal of which is connected to the positive line 10.

lVhen, therefore, the coil K is energized by the closing or" the primary circuit by any one of the contacts 1, 2 and 3, or by the switch D and the coil K lifts the plate K into contact with the jacks L, a circuit is completed across the latter to the coil I which is thus energized. This causes the core J to rock the lever K toward the left (Fig. 5), carrying the contact piece K into contact with the spring yielding jacks 8 and 9, which then yield against springs T. The latter permit the lever K to continue to move to the le -ft after the contact piece K has come into contact with the jacks 8 and 9, so

that, upon further movement of said lever, the contact piece K brings up against the jacks 6 and 7, thus completing the motor circuit and starting the motor. Incidentally,

it will be observed that the yielding springs v i T yield to permit proper alinementoi the contact making piece K A spring K is arranged to hold the lever to the left after it has been moved as just described.

The motor, having thus been started, will continue in operation until, owing to the deenergizing of the coil K caused by the breaking of the primary circuit, the contact plate K again rests on the jacks K hen this occurs, circuit will be completed across these jacks from the positive line 10 to the wire 19, through the jack 9 contact making piece K jacks 8. to the wire 20, coil M and wire 21, to the negative line 14. The coil M, havingthus been energized, will cause the core J to swing the lever K toward the right, said lever carrying the contact piece K out of contact with the jacks G and 7, thus opcn ing the motor circuit and stopping the motor.

It has been found in practice that a carrier on entering a bend at the foot of a. transit tube riser, such as that shown at the right of Fig. 1, and having to overcome the resistance of a contact maker trip such as C is likely to stop at that point and rest on the trip. This does no i rm, however, because it it strikes with sutiicient force to operate and p: t the trip C, said trip will have made a contact of suiliciently long duration to start the motor, and the circuit controller instantly respond to the consequent reduction pressure in the system and will maintain the previously established circuit. It evident that this must be so since the carrie bein in the t ansit tube. whether in motion or n s an ob Lruction, and hence the r shed pressure in the transit tube being communicated to the controller 12, causes the motor to continue in operation until the carri It the car- E wi' charged. rier, as above stated, should stick in operating; the trip C, the spring oi the trip would still yield sullicien .y to allow the trip to close the circuit, whereupon the pump would start and propel the carrier.

i evident t the operation Xow it must be nat oi the circuit closers l. and 3 s nl momentary and simply go; we to start the motor and ini .a cut. and that the to the air c, consequent change or" the air pressure in the system will act upon the c 1 oller E to keep the motor in operation and to maintain the preriously initiated air current. The controller E, h wever, must be given sufiicient time to come into action and, since the switch plate K commence to drop ,e noincnt the coil is deenergizcd, said tch plate would nstantly complete circuit K and might at once stop d switch plate were nermitted to drop without restraint. Any suit able means 111 be provided to re he scent of the switch plate, but her I have shown for such purpose a d: sh pot K which maybe any of the usual typev As .i usti l in Fig". 5. the dash pot comprises a piston cl working in a cylinder K and carried up and down therein by the rod K. The piston is provided with holes S which, when open, permit the tre passage of a suitable fluid such as oil, the ascent of the piston. The descent of the piston, however, is re tarde-d by reason of the closing of the holes S by a suitable valve, herein a plate S car ricd by the red X. and free to move p and down thereon to a limited extent. The moment the latter commences to crop, the plate S closes the holes S, whereupon one only means of escape of the oil from the under side of the piston is the slow leakage about the sides ot the latter and between the plate S and the piston S, and through the holes 55. It follows that the dash pot imposes a restraint upon downward movement of the switch plate, and thus gives the controller E time to act to maintain the previously es tablished motor circuit by rcencrgizing the coil K*. The latter then prevents the switch plate from descending and contacting with the tLClZS K, as would otherwise be the case.

In F ig. 5, there is shown the electric circuit controller E with a pipe connection E to the transit tube B, operating as hereinbefore described in connection with Fig. 1, but it will be understood, however. that an electric circuit controller E (Fig. 6) might be employed that the pipe E would be connected to the sub-atmos )hcric pressure transit tube B, and the pipe i31 to the superatmospheric pressure transit tube or tubes N. From the foregoing description of the devices shown in Figs. 4;, 5 and 6, it will be clear that a diminution of the pressure in he chamber E of the electric circuit controller E to a point below that of the atmosphere, or an increase of the pressure in the chamber 9, or both, by an obstruction of any of the transit tubes by reason of a carrier being despatched, will lift the weight E thus closing the contact D and maintaining the motor circuit. lVhen, however, 0w ing to the discharge of the carriers in transit or by reason of the carrier or carriers outrunning' the air current when descending a tube riser, the motor will be continued in operation during the interval of time consumed by the cu rent of the switch plate K from the j- ...s L to the jacks K and the motor will not stop until the switch plate completes a circuit across the jacks K.

before stated, any suitable form of elec tric controller may be employed, instead of the diaphragm types exemplified by the con trollcrs E and E" (Figs. 2, 3 and 6). For example, manometcrs R (Figs. 8, 9, 10 and 11) may be employed, the column 0 being a conducting fluid such as brine or other suitable liquid. Figs. 8 and 9 show as a substitute for the electric circuitcontroller E a manometer R connected to the transit tubes N. F ig. 8 indicates, by the difference in height of the levels 6 an e, the pressure in the pipe E while the blower is still in operation but with no carrier in the tube, while Fig. 9 indicates by the difference in height of: the levels 0* and c the pressure in the pipe E when there is a carrier in transit. A. similar manometer R is illustrated in To) and 11 connected with the transit 9 s B through pipe E, 10, showing bv the difference of levels 0" and 6 the pressure below that of the atmosphere when the blower is in operation, but no carrier in the transit tube. Fig. 11 shows by the dilfer'ence of levels 6 and c the diminution of pressure to a point below that of the atmosphere when the blower is in operation,

and there is a carrier in the transit tube. In these manometers, the differences of height of the fluid are utilized to complete and interrupt thecircuit by the use of electrodes f shown in Figs. 8, 9, l0 and 11, which, when connected through the conducting fluid e as in Figs: 9 and 11, accomplish the same result as when the contacts I) of the controllers E and E are closed. When the levels are as indicated in Figs. 8 and 9, the circuit is opened, just as in the case of the controllers E and E the opening of the contact D opens the circuit.

While I have herein shown and described certain specific embodiments of my invention for illustrative purposes, and have dis closed and discussed in detail the construction and arrangement incidental to the specific applications thereof, it is to be understood that the invention is limited neither to the mere details or relative arrangements of parts, nor to the specific embodiments herein shown, but that extensive deviations from the illustrated forms or embodiments of the inventionmay be made, without. departing from the principles thereof.

' scribed, a carrier transmission tube, an airmoving device connected thereto, a motor for driving said air-moving device, means remote from the despatching inlet ot'said tube for startingsaid motor, and motor controlling means for keeping the motor in operation and controlled by the differential pressurecreat ed by a carrier or carriers in transit.

3. In an apparatus of the character described, a carrier transmission tube provided with stations for sending and receiving carriers, air moving means connected i thereto, a motor for driving said air moving means, means for energizing said motor, and motor controlling means controlled by the till for continuing the motor in operation due tov thecontinued presence of a. carrier or carriers in transit between said fistations. V

111 an apparatus-ofthe character described, a carrier transmission tube, an air moving device, a motor for driving said air moving device, means forjenergizing said motor, motor controlling means for keeping said motor in operation controlled by the differential pressure due to a carrier in transit, and means for keeping the motor in operation while a carrier is in a portion or" the transit tube where the carrier in transit does not act as an obstruction until the carrier again controls said motor or is discharged from said tube.

5. In an apparatus of the character described, a carrier transmission tube, an air moving device, a motor for driving said air moving device, an automatic motor starting, maintaining and stopping device controlled during a portion of its operation by the pressure due to a carrier or carriers in transit, and a retaining device controlling the second mentioned device during another period or periods of the carrier travel when differential pressure due to the carrier in transit is non-existent.

6. .In an apparatus of the character clescribed, a carrier transmission tube, an air moving device, a motor for driving said air moving device, means for causing said motor to start, motor controlling means for keeping said motor in operation and controlled by the difi'erential pressure created. by a carrier or carriers in transit, and means for causing the restarting of said motor toinsure the delivery of a carrier or carriers in transit.

7 In an apparatus of the character described, a carrier transmission tube, an air moving device, a motor for driving said air moving device, means remote from the despatching inlet for causing said motor to start, motor controlling means for keeping said motor in operation and controlled by the differential pressure created by a carrier or carriers in transit, and means for causing the restarting of said motor to insure the delivery of a carrier or carriers in transit.

8. A carrier transmission apparatus comprising, in combination, a carrier transmission tube, means including an air-propelling device for'moving air through said tube, means for causing the initiation of a carrier-propelling air-current in said tube by starting said air propelling device, and means controlled by the difi'erential pressure created by a carrier or carriers in transit to cause the maintenance of the previously initiated air-currentby keeping said airpropelling device in operation.

9. A carrier transmission apparatus comprising, in combination, a carrier transmission tube, means including an air-propelling device for moving air through said tubemeans for causing the initiation of a carrier-propelling air-current in said tube by starting said air-propelling device, means controlled by the differential pressure created by a carrier or carriers in transit to cause the maintenance of the previously initiated air-current by keeping said airpropelling device in operation, and means for retarding the action of the lastmentioned means.

10. A carrier transmission apparatus comprising, in combination, a carrier transmis' sion tube having two terminals one of which is constantly in communication with the atmosphere, an air exhauster connected to the other terminal, a motor for driving said air exhauster, means for starting said motor to cause the initiation of an air flow from the atmosphere intoand through said tube and into said exhauster, and means controlled by the differential pressure created by a :arrier or carriers in transit to cause the maintenance of'the previously initiated air flow. 1

11. A carrier transmission apparatus comprising, in combination, a carrier transmission tube having two terminals one of which is constantly in communication with the at mosphere, an air exhauster connected to the other-'tern'iinal, a motor for driving said air exhauster, motor controlling means acting through said motor to cause the initiation of anair flow from the atmosphere into and through said tube and into said exhauster, means controlled by the differential pressure createdby a carrier or carriers in transit to cause the maintenance of the previously initiated air flow, and means for opposing a gradually yielding resistance to the resto ation of said motor-controlling means to normal condition.

12. A carrier transmission apparatus comprising, in combination, a carrier transmission tube havingtwo terminals one of which is constantly in communication with the atmosphere, air moving means connected to the other terminal, a motor for driving said air-moving means, motor-controlling means acting through said motor to cause the initiation of a carrier-propelling air flow in said tube, and means controlled by the differential pressure created by a carrier or carriers in transit to cause the maintenance of the previously initiated air flow, the last mentionedm'eans including a pressure reonsive element having one face subject to t e variations in pressure in said tube.

13. A carrier transmission apparatus comprising, in combination, a carrier transmission tube having two terminals one-oft which is constantly in communication with the at mosphere, .air moving means connected to the other terminal, a motor for driving said air-moving means, motor-controlling means acting through said motor to cause the initiation of a carrier-pro e1ling air flow in said tube, means control ed'by the differ ential pressure created by a carrier or carriers in transit to cause the maintenance of the previously initiated air flow, the lastmentioned means including a pressure responsive element having one face subject to the variations in pressure in said tube, and electrical means operated by said pressure responsive element.

14:. A carrier transmission apparatus comprising, in combination, a normally dead carrier transmission tube, air moving means connected thereto, an electric motor for driving said air moving means, electrical motor-controlling means acting through said motor to cause the initiation of an air flow in said tube, and means controlled by the differential pressure created by a carrier or carriers in'transit and acting on said motor-controlling means to cause the maintcnance of the previously initiated air How, the last-mentioned means including a pressure-responsive element subject to variation of pressure in said tube.

15. In an apparatus of the class described, the combination oi? transit tubing in which there is normally no air flow, an air movingdevice connected thereto, means to cause the establishn'ient of an air [low in said transit tubing, and controlling means for causing the maintenance of said air flow, said controlling means comprising a device operated by increase rarefication or comprt sion oi? theair, or both, due to a carrier or carriers in transit.

16. In an apparatus of the class described, the combination of transit tubing in which there is normally no air flow, an air moving device connected thereto, means to cause the establishment of an airflow in said transit tubing, and controlling means for causing the maintenance of said air flow, said controlling means comprising a device operated by increased rarefication or compression oi? the air, or both, due to a carrier or carriers in transit, and means for causing the mainte nance of the air flow during such times as the carrier does not act as an obstruction to the air flow.

17. In an apparatus of the class described, the combination of a vacuum transit tube, a pressure transit tube, an air moving device having an inlet connected to said vacuum tube and its outlet connected to said pressure transit tube, means to cause the establishment of an air flow in said tubes, and controlling means for causing the maintenance oi said air flow, said controlling means comprising a device operated by increased rarefication or compression of the air, or both, due to a carrier or carriers in transit.

18. In an apparatus'o'f the class described, the combination of a vacuum transit tube, a pressure transit tube, an air moving device having an inletconnected to said 'vacuum tube and its outlet connected to said pressure transit tube, means to cause the es- "tablishment of an air flow in said tubes, and

- controlling means for causing the maintenance of saldan' flow, said controlhng means comprising adevice operated by increased rarefication or compression of the air, or

' Jboth, due to a carrier or carriers in transit,

"-andmeans for causing the maintenance of theair flow during such times as the carrier 'does notact'a's an obstruction to the air flow; i

19. In anjapparatus of the character described, the combination of a carrier transmissionytubenormally open to the atmosphere and provided with stations for send- Iing and receiving carriers,- air moving means including a motor connected thereto, means tor starting said motor thereby to establish an air flow in said transmission tube upon the despatchof a carrier and thereafter automatic'allyto stop said motor disestablish said air flow independently of the carrier or carriers in transit, and controlling means rendered effective "by the continued presence of acarrieror carriers in transit between isald stations to cause the. continued operation of said motor and the continuance of? the air flow.

. 20. In an apparatus of thecharacter described, the combination of a carrier transmisslon tube normally-open to the atmosphere and provided with carrier sending and receiving statns,land in Winch there is norvanally no air flow, air moving means con- 1 fnected thereto, means ,for establishing an air flow in' said-transmission tube upon the despatch of a carrier and thereafter auto- Qmatically to disestablish said air flow independently of the carrier or carriers in transit, and controlling means rendered efi'ective by the continued presence of a carrieror carriers in transit between saidstations to cause a continuance of the air flow.

' 21. In an "apparatus of the character described, thecombination or" a carrier trans- 415. v p v T elud ng a motor to cause toe estabhshinent mission tube, airinoving means, means inofain air flovvupon the despatch or a carrier and thereafter automatically to cause the 7 "'disestablishment of'the air fiowindepehd- 5'0 7 gcontroll n' nieansflior causing the ma1nteently otthe carrier or cai iers in transit,

" nance oftheair, flow by controlling said motor, said Ic'ontrolhnp' means bemgoperated *by. the differential pressuredue'to a carrier 5 1 intransit, and meansj i'or delaying the automati c disestablishnient of the air flow While a carrier is in a portlon oi the trans tube i two subscribing Witnesses, this September, A... D. 1914.

Where the carrier does not act as an obstruction until the carrier again controls said maintaining means or is discharged from said tube.

22. In an apparatus of the class described, the combination of a carrier transmission tube, an air moving device, lair flow establishing, maintaining and automatic stopping instrumentalities including a motor concausing the establishment of an air flow,

controlluw means for maintaining said air flow, said controlling means being responsive to the diiiere'ntiai pressuredue to a carrier in transit, and means for causing the re 7 establishment-oi said air flow to lnsure the delivery of a carrier or carriers intransit.

; 2%. In an apparatus'of the class described,

th combination of a carrier transmission tube, means including a motor for establishingan air flow and havingcapacity tor au-' tomatically discontinulng the same upon the lapse oi certain time period, and means controlledby the differential pressure due to a carrier or carriers in transit to continue the operation of said motor-to prevent the running of the time period.

in an apparatus of the character described, th combination of a plurality of transmission tubes each provided 'with stations forsending and receiving carriers, air 7 moving means connected thereto, a motor" for driving said air moving; means, means for energizing said motor, and a single'motor controlling means connected to said tubes for continuings motor in operation due to the continuedpresence of a carrier or carriers in transit inIany one of said tubes.

in testimony whereof I have signed my to this specification in the presence of 24th day of J. x. liiiiCLAREN.

\ 'iVitnesses ELsrn MncLAnsN, Josnrr-r Bison. 

